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Louis Pasteur waged a successful war on disease

Posted in Animals, Discoveries, Historical articles, History, Medicine on Tuesday, 27 November 2012

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This edited article about Louis Pasteur originally appeared in Look and Learn issue number 789 published on 26th February 1977.

Louis Pasteur, picture, image, illustration

Louis Pasteur sees the results of his experiments with a vaccine for anthrax by Peter Jackson

In a remote mountain village in Eastern France mothers snatched their children into the shelter of doorways as the dreaded cry arose: “Mad wolf, mad wolf . . .”

Foaming at the mouth, the crazed animal ran through the village, biting anyone unfortunate enough to be in its path. The incident made a lasting impression on the nine-year-old boy who had watched in horror from behind the window of his home. Young Louis Pasteur knew only too well that within weeks most of those who had been bitten by the rabid wolf would die of the terrible and inescapable sickness of hydrophobia, or rabies.

Later Pasteur went to school in Paris and became obsessed with chemistry. By the time he was 26 he was already carrying out research that was bringing him an increasingly grand reputation, but neither he nor his associates could have guessed that the climax of his life’s work would be the battle against hydrophobia.

Through his work on fermentation – Pasteur was called in by the French wine-growers to help improve the yields and rid the vats of a scum that seemed to prevent the fermentation process itself – the scientist was able to identify a strange rod-like microbe as the cause. Just 1/25,000th of an inch long, this particular microbe was ‘killing’ the yeast microbes.

Much of Pasteur’s work rested on inspired guesses, and now he reasoned that if microbes could do this kind of damage to each other, what might they not do to human beings?

He was also convinced that these microbes were in the air, lying in wait, so-to-speak, for their next victim. With characteristic self-confidence he designed an experiment to prove that the air was indeed thick with tiny ‘bugs’ hostile or otherwise.

He and his assistants heat-sealed scores of bottles containing a ‘yeast soup’, having first expelled the air by boiling over a fire. The soup contained no microbes at all, but if Pasteur was right microbes would get in when the bottles were opened.

The first collection of flasks were opened in the cellars of the Paris Observatory. More flasks were opened in the courtyard of the same building. Then bottles were taken up on the slopes of Mount Blanc and the Jura Alps and opened there!

Pasteur could scarcely contain his excitement; it was the flamboyant style of experiment which his temperament favoured and the more attention it attracted the better. Provided always that it was successful, of course.

Sure enough, the microbes had got into the soup. But the higher the flasks had been taken and the thinner the air, the fewer microbes were to be found. Without doubt, they were airborne, and Pasteur gave a dramatic lecture to that very effect.

“Ladies and gentlemen,” he said, “Look at the dust floating in this beam of light from this lantern projector. These specks of dust could carry typhus, cholera, yellow fever and other terrible diseases . . .”

His audience returned to their homes in subdued mood and Pasteur himself took to very carefully wiping his cutlery with a napkin whenever he was invited out somewhere. Naturally Pasteur’s ideas aroused bitter controversy and many of his experiments were open to scientific question, but there were many men who learned and followed in his steps.

Pasteur was approaching sixty when chance, and more inspired guesswork, gave him the idea that microbes could be turned against each other. His assistants had been conducting a series of tests in which they had been injecting chickens with a virus called ‘chicken-cholera’.

To their astonishment one chicken, which had been injected with an old culture that was harm less about a month previously and which had been brought out only because they had run out of new chickens, survived a further and lethal dose of the disease.

“Don’t you see,” shouted Pasteur, “I have found out how to make a beast a little sick – but so that he will get better.” It was this principle which led Pasteur to produce the first vaccine for the cattle killer disease anthrax.

Unfortunately Pasteur’s enthusiasm for his discovery exceeded his ability accurately to produce the vaccine in large quantities. Within months cows and sheep were dying, even though they had received the doses of the vaccine. In his desire to manufacture as much vaccine as possible and as quickly as possible in his laboratories, Pasteur had failed to ensure the purity of his preparation.

However Pasteur was not to be daunted, and now turned his attention to discovering the virus which he assumed was the cause of hydrophobia. Alas, hours, days and weeks of examining beneath a microscope the saliva of rabid dogs and the tissues of similarly diseased rabbits failed to reveal the responsible microbe.

It was dangerous work. Infected material had to be handled by Pasteur and his assistants; infected animals had to be fed and tended. Liquid mixes of the material had to be sucked up in glass pippeties, and drop by drop, placed on the microscope slides.

Finally, Pasteur deduced that the virus, which seemed to be too small to be seen in the microscope, probably attacked the spinal cord and the nervous system of the brain itself. If that was the case cells from the brain of an infected dog would have to be transplanted into a healthy one. These were not pleasant experiments and Pasteur was often attacked by anti-vivisectionists; yet he was always anxious to spare his animals any unnecessary suffering and in this instance forbade his assistant to carry out the experiment.

But his assistant Roux for once disobeyed his master, and Pasteur was able to establish that the virus did attack the nervous system.

Next a small section of the spinal cord of a rabbit which had died from rabies was removed and dried out in a germ-proof bottle for fourteen days. A dog was given a course of injections starting with the 14-day dried out tissue. Then a further series of injections were given of tissue dried for shorter and shorter periods until on the 14th day the dog received a dose that would have killed him.

The dog did not die. Nor did any other dogs. The vaccine seemed to work. Then on July 6th 1885, at the request of the distraught mother of 9-year-old Joseph Meister who had been badly bitten by a mad dog. Pasteur gave the lad a series of injections. Young Joseph survived and all Europe rejoiced.

Pasteur, who lived on for another ten years but whose great work was now done, had made his own incalculable contribution in the fight against disease.

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